List of All Known Mutual Zugzwangs

Each endgame names White's pieces in Q-R-B-N-P order folllowed
by Black's pieces in the same order.
White is chosen to have at least as many pieces as black.
If the number of pieces on each side are equal, the Q-R-B-N-P order
determines White (eg, KQRKQB rather than KQBKQR).

For positions
in symmetric-force
endings, White is arbitrarily chosen as the side with the first piece
(in the order above) on the first square (a1-h1, a2-h2, etc).

Where there is more than one bishop, a "bishop signature" is added
of the form "_abcd". This indicates `a' white and `c' black Bishops of
one square-color, and `b' white and `d' black Bishops of the other
square-color, where a>=b and c>=d if a=b.

The maxDTC/maxDTM columns are the maximum DTC/DTM (depth to
conversion/mate) of any mzug for that ending with the losing side to play.
The values are only available for the endings which have been analyzed by
the respective data sources. Where depths are not provided from the source,
they are looked up in Eugene Nalimov's DTM EGTs and Christopher Wirth's
DTC EGTs.

Sources:

PK - Peter Karrer (using Eugene Nalimov's EGTs as well as his own KQQKQP DTM EGT)

LR - Lars Rasumussen

LS - Lewis Stiller

JT - John Tamplin (using Eugene Nalimov's EGTs as well as his own DTC EGTs)

KT - Ken Thompson

CW - Christopher Wirth

No data sources contradict each other, so we believe this list to be
complete for the endings listed and without error. Any endgame not listed
with less than 6 pieces is known to have no mutual zugzwangs, as are
KBBKBB, KBBBKB, KBBBKN, and KQQKRB (for which only btm/1-0 is known). If you
are aware of
any mutual zugzwang that is not listed on this site or you find any error
in this data, please email me at
jat@jaet.org.

Ken Thompson's encoding used for his data does not differentiate between
black losses and draws, so it is not possible to detect full-point mzugs
using only his data. For those endings where KT's data is the only available
source and black has sufficient mating material, we have assumed that there
are no full-point mzugs. Hopefully, we
will soon be able to verify this from additional data sources.